Defibrator



Oct. 15, 1968 A. .1. YLl-PAAVOLA 3,405,876

DEFIBRATOR Filed Sept. 22, 1966 United States Patent 3,405,876DEFIBRATOR Antti .luhani Yli-Paavola, Tampere, Finland, assignor to 0yTampella Ah, a corporation of Finiand Filed Sept. 22, 1966, Ser. No.581,244 Claims priority, application Finland, Dec. 9, 1965, 2,964/ 65 4Claims. (Cl. 241255) This invention relates to a defibrator particularlyfor refining paper stock and the object of the invention is to provide adefibrator which is more effective and gives a better product thandefibrators heretofore used.

The principal characteristics of the defibrator according to theinvention are set forth in the accompanying claim 1.

In the Finnish Patent No. 33,051 is a refiner disclosed particularly forthe refining paper stock, in which the diameters of the various zonesincrease in the feeding direction, but in which the surfaces of thezones are parallel to the axis of the rotor, in which case it is notpossible to achieve a continuously accelerating movement of stock duringits movement in each zone and therefore not an improved defibrationsimultaneously with substantial decrease of the passage time of stock,the result improving irrespectively.

In the German Patent No. 1,177,466 a disc refiner is disclosed whereinthe refining discs are divided into zones which in the direction of thedisc axis are displaced with respect to each other and in which the gapin each zone decreases towards the perifery, and at the transit from onezone to another there is an axial transit zone consisting of plates, thegap in said transit zone being, however, equal to the gap in theprevious zone, so that no pressure drop results in the stock stream.

The invention is described more fully in the following, with referenceto the accompanying drawing which as an example shows a defibratoraccording to the invention in longitudinal section.

In the drawing the reference numeral 1 indicates a rotor of thedefibrator and 2 a stator drum, which both are divided into threeconical zones 3, 4, 5 and 6, 7, 8 respectively. At the feed end of therotor 1 there is provided a screw feeder 9 rotating together with therotor and located in a feeding channel 11 situated at the center of ahousing 10. The stator 2 is lbolted by the bolt 12 to the housing 10.The housing in turn is through an intermediate ring attached to a frame14 by means of bolts 15, thus forming adjacent the intermediate ring astock discharge space 16 of the defibrator, from which space the stockis discharged in a known manner.

The base angle of the cones of the conical zones of the rotor and stator3, 4, 5 and 6, 7, 8, respectively is greatest in zones 3 and 6 anddecreases being smallest in zones 5 and 8. At the transit from oneconical zone of the rotor 1 to another the base portion of zones 3 andWee 4 have cylindrical zones 17 and 18 which each terminate at walls 19and 20 perpendicular with respect to zones 17 and 18 and defining thezones 4 and 5 respectively, opposite which walls 19 and 20 and at adistance from them cor-responding to the width of the zones 17 and 18the stator 2 has corresponding parallel walls 21 and 22 and cylindricalzones 23 and 24 parallel to zones 17 and 18. Thus there are formed twoannular extensions or pockets 25 and 26, greater than the normal gapbetween the rotor 1 and the stator 2 at the travel path of the stock.

As the stock stream moves between the stator and the rotor at increasingspeed in each zone and reaches the extension there occurs a suddenpressure drop in the stock and further a relatively great change of flowdirection, which facts have a favourable influence on the breaking up ofeventual fibre bundles.

The invention is not restricted to the embodiment described and shownonly as an example but can be modified in many ways within the scope ofthe accompanying claims. Thus e.g. zones 18 and 17 need not necessarilybe parallel to the rotor axis but can have a conicity similar to that ofthe zones 3 and 4 or even differing from the same.

What I claim is:

1. Defibrator particularly for refining paper stock, comprisingrotatable rotor provided with bars and a stationary stator drum mountedaround the same and preferably provided with bars, the rotor and statorboth being divided into at least two zones having an increasing diameterin the feeding direction of the stock, characterized in that the zonesare conically widening in the feeding direction and that the base angleof the cone decreases from zone to zone in the feeding direction of thestock.

2. The defibrator according to claim 1, characterized in that at thetransit point between zones there is an extension greater than the gapbetween the rotor and the stator elsewhere.

3. The defibraor according to claim 2, characterized in that the crosssection of the extension at the transit point between zones isrectangular.

4. The defibrator according to claim 3, characterized in that thesurface of the rotor adjacent to the extension is parallel to the axisof the rotor and that the extension extends to the feeding gap of thefollowing zone.

References Cited UNITED STATES PATENTS 1,971,335 8/1934 Benner et a1241-255 X 2,824,500 2/1958 Cumpston 241255 X 3,162,385 12/1964 Baxter241260 X WILLIAM W. DYER, JR., Primary Examiner.

F. T. YOST, Assistant Examiner.

1. DEFIBRATOR PARTICULARLY FOR REFINING PAPER STOCK, COMPRISINGROTATABLE ROTOR PROVIDED WITH BARS AND A STATIONARY STATOR DRUM MOUNTEDAROUND THE SAME AND PREFERABLY PROVIDED WITH BARS, THE ROTOR AND STATORBOTH BEING DIVIDED INTO AT LEAST TWO ZONES HAVING AN INCREASING DIAMETERIN THE FEEDING DIRECTION OF THE STOCK, CHARACTERIZED IN THAT THE ZONESARE CONICALLY WIDENING IN THE FEEDING DIRECTION AND THAT THE BASE ANGLEOF THE COME DECREASES FROM ZONE TO ZONE IN THE FEEDING DIRECTION OF THESTOCK.